How to position CT clamps correctly so solar does not interfere with EV charger. | on ElectriciansForums

Discuss How to position CT clamps correctly so solar does not interfere with EV charger. in the UK Electrical Forum area at ElectriciansForums.net

rwdl1984

DIY
Joined
Aug 16, 2022
Messages
7
Reaction score
3
Location
Edinburgh
We recently had a solar panel system put it in. The solar batteries were delayed and put in after, at which point it became clear that the CT clamp for the solar system was positioned on the wrong cable. The inverter was reading the power generated by the solar system and including it in the house load, causing the batteries to discharge rapidly etc etc.

The solar company (finally) came back and moved the CT clamp to live 1 between the fuse and meter. This sorted out the issue with the inverter and batteries. Sadly, it has caused issues with our existing EV charger. The EV charger ramps up to around 5.5 kW then cuts out. The electrician from the solar company positioned the solar CT clamp right above the EV CT on live 1. He mentioned briefly at the time that they might interfere with one another.

I'm posting this now because the solar company has gone AWOL and are refusing to come back to fix things. Perhaps there is a simple fix here, without me having to convince a new company to and fix this? Does anyone know the correct position for the solar CT clamp that won't cause the EV charger to cut-out?

I have already tried moving the solar CT clamp further up the cable away from the EV clamp (as suggested in other posts), but this has not made a difference. Please see the attached image. The blue circle at top right shows where the solar CT clamp was positioned originally by the company, but this resulted in incorrect power readings on the inverter. The two CT clamps are together on live 1 now, the EV one is the one below.

Any suggestions would be much appreciated!
 

Attachments

  • [ElectriciansForums.net] How to position CT clamps correctly so solar does not interfere with EV charger.
    IMG-8256.jpg
    483.9 KB · Views: 650
I was going to sayEasy fix. One can be positioned after meter, but the hendley block takes two feeds out.

where do the two feeds go? one is the main board what is the other. Could it be separate board for pv or car charger?

if the solar pv is wired directly into the main board add one clamp to the main boards feed tail after the meter.
 
I think we need a simple system diagram. Basically - is the solar wired what I call the old way, straight into the main board, or does the solar have it's own consumer unit?

(Finally be careful of that hole in the side of the consumer unit, you should get that plugged)
 
I was going to sayEasy fix. One can be positioned after meter, but the hendley block takes two feeds out.

where do the two feeds go? one is the main board what is the other. Could it be separate board for pv or car charger?

if the solar pv is wired directly into the main board add one clamp to the main boards feed tail after the meter.
Thank you so far - please see the wider shot attached below. The units on the left are for our air source heat pump (not currently in use/drawing power). The ones directly above the meter I believe are for the solar/inverter. As you say one feed is going into main board, the other seems to be going into solar and heat pump isolators.
 

Attachments

  • [ElectriciansForums.net] How to position CT clamps correctly so solar does not interfere with EV charger.
    IMG-8260.jpg
    408.8 KB · Views: 378
Are you saying it WAS where the red circle is?
[ElectriciansForums.net] How to position CT clamps correctly so solar does not interfere with EV charger.


To my understanding, to measure the output from the inverter it needs to be where the green circle is.

My other concern is that you appear to be missing some absolutely essential safety labelling warning of two sources of supply.
 
Yes, originally the CT clamp for the solar/inverter was in the red position - this resulted in the inverter showing a very high load in the house (it was including the power produced by the solar panels in the house load, causing the batteries to discharge to compensate). However, the EV charger worked fine.

Should I move a CT clamp to the green-circled cable, and if so, which one, solar or EV clamp?

I'm not surprised by the lack of stickers - I'm not at all impressed by the company we hired.
 
I should qualify that I have limited experience with solar, having only connected up a couple of Zappi systems.

In general terms I'd expect the EV CT clamp to be where it is, the purpose being to monitor the demand of the whole installation to comply with any grid limits that are set.
I'd expect the solar generation sensor CT clamp to be where the green circle is to monitor the invert output.

The arrow direction matters on the clamps, the EV CT clamp should point towards the consumer unit and the solar CT clamp should point towards the black connection block. So the two arrows should be pointing at each other if you follow along the cable.

At least, that is how Zappi works.
 
Have you tried sliding the upper CT up the cable so it is closer to the meter and not sitting on top of the other one? You could put a cable tie round the cable to stop it sliding back down.

It's always worth trying the simple things first.
Yes, I tried that and it made no difference, I think that was stated in my original post.
 
You probably did and I just didn't read it properly.

You could also try putting one on the neutral, just flip it around so the arrow is in the other direction.
Why didn’t I think of that. of course either I was having a senior moment or your a genius. First time I’ve put a creative and not meant it to be condescending.

TBH I think that one was down to my lack of thinking.
 

Reply to How to position CT clamps correctly so solar does not interfere with EV charger. in the UK Electrical Forum area at ElectriciansForums.net

News and Offers from Sponsors

  • Article
Join us at electronica 2024 in Munich! Since 1964, electronica has been the premier event for technology enthusiasts and industry professionals...
    • Like
Replies
0
Views
459
  • Sticky
  • Article
Good to know thanks, one can never have enough places to source parts from!
Replies
4
Views
1K
  • Article
OFFICIAL SPONSORS These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then...
Replies
0
Views
2K

Similar threads

I am living in the north of Thailand where the grid is very unreliable (rainy season outages multiple times per week or once a full week). I...
Replies
0
Views
470

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
Back
Top